In general, it is desirable that a sliding surface is a smooth surface in order to reduce friction in the sliding surface. When, however, the sliding surface becomes smooth, frictional resistance is limited to a low one. On the other hand, heat occurs in some degree at the sliding surface so that there is a risk of a generation of adhesion by so-called seizing. Accordingly, the sliding surface is required to have any suitable surface roughness.
In the past, a shot blasting against the sliding surface to form any recesses thereon has been a well-known technology. A technology to form an oil reservoir on a sliding surface of the sliding member by shot blasting has been known (see, for example, the patent document 1).